Ok here goes with my 2nd post to this forum, i.e. I'm new at this. Please bear with me if I've got some terms wrong. My question is in regard to what the crossover on your sub actually does? I have a Sherwood 6106 and Fidek make sub (I know low end stuff). From memory the sub has adjustable crossover from ~40 - 120 Hz. From what I've read from similar questions is that if my receiver is fixed at say 80 Hz (guessing) does that mean that if I set the sub at above this then in effect it isn't really doing anything? However if I do just that I do notice/feel more "sound", i.e. amplitude of the cone is increased greatly (in fact the difference is significant say with comparison at ~90 and 120 Hz), so is it actually doing something then or why then is it? Thanks in advance.